The invention relates to a quartz controlled analog wrist watch comprising a quartz controlled pulse generator and a driving element for driving a first toothed wheel of a gear train, said driving element being mounted for pivoting about an axis, a coil connected to receive the output pulses of the pulse generator, and a permanent magnet, which are movable relative to each other, for deflecting said driving element from a rest position and further comprising a reset spring to swivel back the driving element.
In a quartz wrist watch of the aforementioned kind (Quartz Wrist Watch Arctos-QUARTZ by the firm of Philip Weber KG, Pforzheim, Germany) the driving element has the form of a conventional, coil-carrying balance wheel of an electric wrist watch, and a conventional hairspring is provided as reset spring. The driving element indexes a second wheel of the gear train by means of a conventional pin-type escapement, and one indexing step is effected during each half-cycle.
It is also already known to provide quartz controlled clocks (desk, wall and alarm clocks) with a driving element which swings to and fro and indexes a second wheel of the gear train directly, so that these clocks have a jumping second hand (see German Utility Model Specification No. 7,146,975). In such cases too, the pivotable driving element carries a coil which cooperates with a permanent magnet and under the influence of electrical impulses occuring at one second intervals deflects the driving element from its rest position against the action of a reset spring, whereupon the driving element is then returned by the reset spring. When the driving element is deflected from its rest position, not only is the reset spring tensioned, but also the second wheel is simultaneously indexed one step further by means of a pawl mounted on the driving element. This principle is disadvantageous in that relatively powerful driving impulses are required, since not only the indexing resistance of the gear train has to be overcome, but also the reset spring has to be tensioned simultaneously.
However, a quartz controlled clock is also known wherein a coil-carrying driving element which swings to and fro relative to a permanent magnet tensions only a reset spring when it is deflected from its rest position by the electrical pulses occuring at 1 second intervals; in this case, the reset spring which is in the form of a leaf spring swivels an indexing lever mounted coaxially with the second wheel, said indexing lever carrying a pawl by means of which it indexes the second wheel one step further when the reset spring swivels back the indexing lever and the driving element (see German published patent application No. 2,408,538).
The success of quartz controlled wrist watches is mainly due to its theoretically high accuracy, since in advertising it is argued that the time error amounts to a maximum of a few seconds per month. This, however, is not the case with known analog wrist watches because, even during normal use, the components of a wrist watch are exposed to considerable accelerations, and practice has shown that the torque occurring at the rotating or swinging driving elements and at the second hand of a wrist watch may be quite sufficient to index it by one second even without an electrical impulse. However, this makes the theoretical high accuracy of a quartz controlled analog wrist watch unachievable. This applies to a far greater extent to wrist watches which are exposed to heavy vibrations transmitted to the hands and arms of the person wearing the watch, for example, when operating certain machinery or riding a bicycle or motor bike.